Rhei Rhizoma is a kind of crude drug previously known, and used frequently in traditional chinese prescription (Kampo). The Rhei Rhizoma is so far known to possess an antibacterial effect, blood urea nitrogen-decreasing activity and anti-inflammatory effect. In the prior art, in order to obtain substances providing such effects, various compositions and/or compounds such as sennoside A have been isolated from Rhei Rhizoma. However, among the compounds isolated from Rhei Rhizoma, no components usable for treating mental disorders have been previously known at all.
Whereas, the following chemical compounds have been known as antipsychotic drugs used for treating schizophrenia:
Levomepromazine, chlorpromazine and thioridazine showing strong sedative effect; perphenazine, fluphenazine and haloperidol showing strong anti-hallucination and -delution effects; and sulpiride having mild sedative effect, and anti-hallucination and -delution effects. These drugs have been selectively used, according to their respective characteristics, in response to patient's symptoms and the progress of disease. However, it has been well-known that these drugs produce adverse effects which are extrapyramidal syndrome such as muscle rigidity, dyskinesia and parkinsonism, and autonomic symptoms such as salivation, dry mouth and constipation. Consequently, a drug without adverse effects for treating mental disorders has long been desired to be developed.